This invention relates to a method of establishing a blasting arrangement, apparatus for use in establishing a blasting arrangement and a blasting method.
The assignation of time delays to individual detonators, used in blasting operation, whether open cut or underground, can be labourious, an aspect which is compounded when use is made of more than one detonator in a blast hole. The integrity of the connection of each detonator to a trunk line must be tested and the functionality of each detonator must be tested. These are time consuming processes which demand close attention to detail and a great deal of care.
The invention is concerned with an improved method of establishing a blasting arrangement.
In the first instance the invention provides a method of establishing a blasting arrangement which includes the steps of loading a plurality of detonators into a plurality of blast holes with at least one detonator being located in each respective blast hole, placing explosive material in each blast hole, connecting a control unit that has a power source that is incapable of firing the detonators to a trunk line, sequentially connecting the detonators, by means of respective branch lines, to the trunk line and, once each detonator has been so connected to the trunk line, leaving the detonator connected to the trunk line.
The detonators may be connected in any desired sequence to the trunk line.
The method may include the step of recording identity data, pertaining to each respective detonator, in the control unit.
The aforementioned identity data may be recorded in the control unit at the time the respective detonator is connected to the trunk line.
The identity data may be recorded in a predetermined order.
The method may include the step of using the control unit, at the time a detonator is connected to the trunk line, to test the integrity of such connection. The functionality of the connected detonator may also be verified.
Subsequently the method may include the step of testing the integrity and functionality of the array of detonators which have been connected to the trunk line.
The invention may include the step of assigning a time delay period to each respective detonator. The time delay period may be predetermined, for example in accordance with the provisions of an appropriate algorithm, or may be assigned under the control of an operator, to achieve a desired blasting pattern or sequence.
The assigned time delay periods may be displayed graphically, at the time of assignation, on a suitable display. Optionally the time delay interval between time delay periods of adjacent detonators may also be displayed.
The invention may include the step of storing data relating to the detonator identity and the time delay period associated with such a detonator in a memory module which may be detachable from the aforementioned control unit.
According to a variation of the invention the method includes the step of receiving co-ordinate data to identify the physical or geographical location of each detonator and storing such data. The co-ordinate data may be received at least in part from any suitable source such as a global positioning system. The co-ordinate data may include three-dimensional data relating to the position of each detonator and its depth from a reference point. Thus the data may inter alia reflect the position of the blast hole and the depth of the detonator in a blast hole, as opposed to the depth of the blast hole.
In a preferred embodiment the data is represented, at least for display purposes, in a regular pattern which is based on the relative positions of the detonators. Preferably the detonators are represented as being in a two dimensional rectangular array of rows and columns and time delays are assigned to the detonators in a progressive manner working from a starting position in the array to a finishing position.
According to a second aspect of the invention there is provided apparatus for use in establishing a blasting arrangement which includes a trunk line, a plurality of branch lines connected to the trunk line at spaced intervals, and a plurality of detonators which are respectively connected to the branch lines with at least one detonator per branch line, the apparatus including a control unit having memory means, a power source that is incapable of firing the detonators, means for receiving identity data from each detonator as the detonator is connected to the trunk line and for storing the identity data in the memory means, means for generating a signal to test the integrity of the connection of the detonator to the trunk line and the functionality of the detonator, and means for assigning a predetermined time delay to each detonator, the assigned time delay being stored in the memory means together with the identity data of the respective detonator.
The memory means may be detachable from the remainder of the control unit.
The apparatus may include display means for displaying at least the time delay which is assigned to each detonator.
The time delay assigning means may include means for incrementing one or more preset time periods, in a controllable manner, to assign a predetermined time delay to each detonator.
The invention also provides a blasting method which includes the steps of sequentially connecting a plurality of detonators by means of respective branch lines to a trunk line, at the time of connecting each detonator using a control unit which is connected to the trunk line to verify, at least, the integrity of each connection and the functionality of the respective detonator, receiving data, transmitted from each respective detonator, pertaining to its identity, assigning a respective predetermined time delay period to each detonator, storing the identity data of each detonator and its assigned time delay period in a memory module, disconnecting the control unit from the trunk line, connecting a firing unit to the trunk line, powering energy storage means at each respective detonator by means of the firing unit, transferring to each detonator its respective assigned time delay period, and using the firing unit to initiate the firing of the detonators.
The invention may, by way of example, also extend to a control unit which includes a barcode scanner for obtaining identity data from a readable bar code corresponding to the identity number of the detonator provided that in use of the detonator, the bar code protrudes from the blast hole in which the detonator is located or is otherwise positioned so that the bar code is readable.
In a variation of the aforementioned technique use may be made of a passive transponder in respect of each detonator. The passive transponder may be incorporated in the electronic circuit which is used, within the detonator, to control the delay period and to monitor safety features. The transponder is interrogated by means of a suitable signal and, once interrogated, transmits a signal which contains the identity data and which is received by a receiver which automatically extracts the identity number. The identity data can then be transferred directly to a memory module without human intervention.
The invention also provides a control unit for use in a blasting system which includes a plurality of detonators, the control unit including memory means for storing at least one time interval, means for adjusting the time interval, means for displaying a time delay period, means for varying the displayed time delay period at least by steps with each step corresponding to the stored time interval, thereby to achieve a desired time delay period, and means for associating the desired time delay period with a selected detonator.
The memory means may store a plurality of different time intervals.
Each of the stored time intervals may be independently adjustable. The stored time intervals may be increments or decrements.
The stored time interval may be adjusted to correspond to the time delay between detonators of adjacent blast holes. Alternatively, where the detonators have been connected by means of branch lines, the stored time intervals may be adjusted to correspond to the time delay between adjacent branch lines.